linux-kernel - Re: [PATCH] uprobes: fix kernel info leak via "[uprobes]" vma

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Message-Id: <20240929223956.5043f74bc781a124e761f013@kernel.org>
Date: Sun, 29 Sep 2024 22:39:56 +0900
From: Masami Hiramatsu (Google) <mhiramat@...nel.org>
To: Oleg Nesterov <oleg@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Catalin Marinas
 <catalin.marinas@....com>, "Liao, Chang" <liaochang1@...wei.com>, Will
 Deacon <will@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] uprobes: fix kernel info leak via "[uprobes]" vma

On Thu, 26 Sep 2024 18:29:01 +0200
Oleg Nesterov <oleg@...hat.com> wrote:

> xol_add_vma() maps the uninitialized page allocated by __create_xol_area()
> into userspace. On some architectures (x86) this memory is readable even
> without VM_READ, VM_EXEC results in the same pgprot_t as VM_EXEC|VM_READ.

Good catch!
I think we push this urgently and send it to stable tree too, right?

Fixes: d4b3b6384f98 ("uprobes/core: Allocate XOL slots for uprobes use")
Cc: stable@...r.kernel.org

Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>

Thank you,

> Reported-by: Will Deacon <will@...nel.org>
> Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> ---
>  kernel/events/uprobes.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 2ec796e2f055..4b52cb2ae6d6 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -1545,7 +1545,7 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
>  	if (!area->bitmap)
>  		goto free_area;
>  
> -	area->page = alloc_page(GFP_HIGHUSER);
> +	area->page = alloc_page(GFP_HIGHUSER | __GFP_ZERO);
>  	if (!area->page)
>  		goto free_bitmap;
>  
> -- 
> 2.25.1.362.g51ebf55
> 
> 


-- 
Masami Hiramatsu (Google) <mhiramat@...nel.org>